1. Field of the Invention
The present invention relates to an electric power steering assembly and a fabrication method thereof.
2. Description of Related Art
An electric power steering assembly is generally designed to transmit an output rotation of an electric motor to a steering mechanism via a reduction mechanism including a driving gear and a driven gear accommodated in a gear housing. The electric motor is normally constructed independently from the reduction mechanism. Hence, an output shaft is previously assembled to the electric motor (motor assembly) and then, the output shaft thus assembled is coupled with the driving gear of the reduction mechanism via a joint. More recently, however, a new design directed to the size reduction of the assembly has been proposed, wherein the joint is eliminated while the output shaft of the electric motor is integrally formed with the above driving gear (see, for example, Japanese Unexamined Patent Publication No. 2003-113909 laid open on Apr. 18, 2003 by Japan Patent Office).
In this case, the assembly is assembled as follows. The output shaft is first supported by the gear housing via a bearing and then, is assembled with a rotor. The rotor is inserted in an inside circumference of a stator previously fixed on a motor housing. In this state, the motor housing is fixed to the gear housing.
According to the above publication, however, the following problems are encountered when the rotor is assembled in the stator. Due to the magnetic force of magnets of the rotor, the rotor is attracted toward the stator so that the rotor is not smoothly inserted in the inside circumference of the stator. This makes the assembly work cumbersome. Furthermore, there is a potential fear of the rotor brought into violent contact with the magnets as attracted by the stator. As a result, the rotor may be damaged.
It may be contemplated to employ jigs to retain the rotor and the stator thereby preventing the rotor from being attracted toward the stator. However, this approach requires additional labor for removing the mounted jigs.
In view of the foregoing, it is an object of the invention to provide an electric power steering assembly designed to reduce the labor involved in the assembly work and to prevent the damage on the electric motor, as well as to provide a fabrication method thereof.